Friday, 16 October 2015

Exceptionally preserved Early Cretaceous mammal

There's an ongoing theme/belief in vertebrate palaeontology that if you want to work on Mesozoic mammals, you have to like teeth. This stems from the fact that a large number of early mammal or mammaliaform fossils are actually teeth, and the different species, genera, or even families are primarily distinguished from each other due to the features of their different teeth, and in particular their molars. This can be related to their exact dental formula (i.e. how many incisors, canines, premolars and molars they have), the number of cusps found on specific teeth, etc. In fact, many names of species or families come from the teeth: Morganucodon, one of the best known early mammals means "Glamorgan tooth", from the Vale of Glamorgan in Wales where it was first found, identified first by a tooth; and eutriconodonts have three ("tri") cones or cusps ("con") on their teeth, while many more end with "dont" or "don" or "dens", all different ways to say teeth.

This is not to say that these animals are known only from teeth. Morganucodon for example is known from many bones. Unfortunately, in the area of Wales where they are commonly found, the skeletons are all broken up and the bones are often broken, and always separated from each other (disarticulated), making it difficult to do more studies with them. However, once in a while, a very well preserved Mesozoic mammal pops up, which is where Spinolestes xenarthrosus comes in. Described this week in Nature by Thomas Martin and colleagues, this new mammal is very interesting.
Fossil of Spinolestes xenarthrosus from Martin et al. (2015).
Spinolestes xenarthrosus is a newly described eutriconodont mammal from the Early Cretaceous of Spain. The skeleton reveals a variety of functional features, suggesting Spinolestes was a proficient mover on land, and may have dug into the ground when necessary, but not necessarily adapted for this kind of lifestyle as it lacks the dental and skeletal characters typically associated with animals that habitually live underground. It had vertebrae similar to those found in xenarthrans (anteaters, armadillos and sloths), a condition that it evolved convergently (meaning the existence of this feature in both groups is not due to shared ancestry, but rather it evolved twice). While these are all interesting features, what is the most remarkable about this specimen is the soft tissue and integumentary structure preserved.

Spinolestes, amazingly, has a number of organs preserved including the outer ear, and possible lung, and liver tissue. The authors have even identified the presence of a muscular diaphragm. Spinolestes is characterized by having a mane containing long “guard hairs” along the neck and shoulder region, and longer hairs along the middle of the back and tail, making a hairy crest along the midline of the animal, while the rest of the body is covered in more typical shorter, soft underfur. In addition to these hairs, it also had “protospines” along the back of the hip-region, which are larger than hairs and formed by several smaller hair-like filaments merging together, similar to how spines are formed in modern mammals like hedgehogs. These features in combination show that mammals evolved this covering of a softer undercoat, denser and thicker guard hairs, and stiffer spines already in the Early Cretaceous, relatively early on in mammal evolution, a feature that is still seen in mammals today.
Lifelike reconstruction of Spinolestes xenarthrosus by Oscar Sanisidro
Martin T, Marugán-Lobón J, Vullo R, Martín-Abad H, Luo Z, Buscalioni AD. 2015. A Cretaceous eutriconodont and integument evolution in early mammals. Nature 526: 380-384. 

Tuesday, 13 October 2015

In Honour of Ada Lovelace - Female Palaeontologists

Today is Ada Lovelace Day. Many of you (like me initially) may not know who Ada Lovelace was, or what the day symbolises. Ada Lovelace was a British mathematician, who is widely regarded as being the first computer programmer. In 1842, she translated and expanded on an Italian article on the "Analytical Engine", a machine invented by her friend, the inventor Charles Babbage. This article contained such thorough and advanced notes and are attributed with including the first algorithm to be carried out by a machine, and were inspiration for Alan Turing's work on the first modern computers in the 1940s.

Living in the 1800s, this was a massive feat for women in science. Ada Lovelace Day aims to celebrate and recognise the achievements made by women in STEM fields - that is science, technology, engineering, and math. Some obvious examples come to mind of scientific achievements by women throughout history, including (but not limited to): Marie Skłodowska Curie (commonly known as Marie Curie), who was the first female Nobel prize winner known for her research in radioactivity; Rosalind Franklin, whose discoveries in chemistry and x-ray crystallography were integral in the understanding of the structure of DNA; Jane Goodall, who has done wonders in our understanding of modern primate behaviour, and ecology; and of course Mary Anning, whose fondness for fossils on the beaches of Lyme Regis lead to a number of scientific discoveries and the recognition of the Jurassic Coast World Heritage Site.

Aside from Mary Anning, there are a large number of female palaeontologists who have made exciting discoveries, and are continuing to do pioneering research. This is by no means a complete list, but here are a few female palaeontologists that have inspired me, and have made significant contributions to the field:

Kay Behrensmeyer (AKA Anna K. Behrensmeyer)

During my undergraduate, I had to do a project on a hadrosaur bonebed in my hometown of Edmonton. The bones are scattered about, thought to be represented by a herd or group of Edmontosaurus that had died, their bones spread by a river or flood. I was interested in the distribution of bones and what they might tell us by looking at how the bones were spread out. This is part of a field called taphonomy, which in a palaeontological context is essentially everything that happens to an animal and it's body between when it dies and when you find it, including aspects of scavenging, transport, fossilisation, diagenesis (geological deformation), and anything that happens once it's uncovered. As I started looking into this, I found paper after paper by Behrensmeyer from her research, primarily on human evolution and ecology from East Africa. Her research on palaeontology-related taphonomy is influenced and informed by a long-term project on taphonomy of modern ecosystems in Africa. She has gone on to write books and book chapters on taphonomy, with many of her characterisations and observations becoming the pillar of modern taphonomic research. Today, she continues to look into taphonomy of palaeo-ecosystems and reconstructing and comparing ecosystems through time. Her work has been absolutely vital in understanding many aspects of past ecosystems and paleo-ecology. She is currently the Curator of Vertebrate Paleonotology and Taphonomy in the Smithsonian National Museum. 

Emily Rayfield

Emily Rayfield is currently one of my supervisors in my PhD, and is a Professor at the University of Bristol. Her research focuses on biomechanics and how you can use it to determine function, often using modern animals to inform on fossils. She is well-known for kick-starting the use of Finite Element Analysis (FEA) in order to understand fossil skulls, such as looking at stress and strain, and further deduce feeding strategies. Much of her work focuses on computed tomography (CT) scans to look at the structure of bone, and how this can inform us on locomotion and function of extinct animals. Rayfield also works on how function and ecological diversity change through time, and has worked on a large number of vertebrate groups including non-avian and avian dinosaurs, mammals, fish, crocodylians, and much more.

Mary Leakey

Matriarch of the famous Leakey family, Mary Leakey was integral to our understanding of primate evolution from the family's research in the Olduvai Gorge of East Africa. She discovered the first skull of Proconsul, an extinct ape thought to be on the branch of primates leading to hominids, as well as Zinjanthropus, a robust australopithecine hominin (much closer to Homo than Proconsul). Leakey was also responsible for finding and classifying a number of stone tools found at various hominin sites, and the Laetoli footprints, a very famous trackway showing three individuals walking (2 side-by-side, one walking in the footsteps of another) of hominin with a human-like gait from 3.7 million years ago. These tracks showed without a doubt that hominins had evolved bipedality (walking on 2 feet rather than 4) by this time, a significant find. Mary Leakey's work stretched both the fields of palaeontology and anthropology, more widely regarded as a palaeoanthropologist, and was essential in our understanding of primate and hominid evolution.

Jenny Clack

The evolution of tetrapods (vertebrates living on land, having 4 limbs rather than fins) has long been a hot-topic of study in palaeontology. We know that life started in the water, and the first vertebrates were fish, but how did they get onto land? Jenny Clack has devoted her career to understanding this transition, looking at early tetrapods during the Devonian and Carboniferous, and has been integral in understanding this important period of the Earth's history.   Some examples of her work include discovering more material and recognising the importance of Acanthostega, a primitive tetrapod with transitional features including both fish and tetrapod features, and the slightly younger Ichthyostega, another primitive, transitional tetrapod, both of which are from Greenland. Clack has also spent a lot of time in search of fossils from "Romer's Gap", a so-called gap in the tetrapod fossil record during the Late Devonian and Early Carboniferous, an important time in tetrapod evolution. Her work has helped to fill this gap and has populated the "gap" with many more fossils. Jenny Clack's research has vastly improved our understanding and knowledge of early tetrapod evolution, and how fish first came out of the ocean and onto land.

Of course, I don't have time to talk about all of the great female palaeontologists out there, but I wanted to feature those four as particularly inspiring or important in my mind. Below is a list of other female palaeontologists that I know (not including students, or the list will never end), and by all means is not a comprehensive list, but are some that I thought of and wanted to feature. I'm open to suggestions to add to the list, but I can't feature all of them! There are too many, which I think means we're doing a great job!

  • Victoria Arbour 
  • Charlotte Brassey
  • Jen Bright 
  • Marie-Céline Buchy
  • Anusuya Chinsamy-Turan
  • Kristi Curry-Rogers
  • Allison Daley
  • Susan Evans
  • Catherine Forster
  • Pam Gill
  • Ursula Göhlich
  • Anjali Goswami
  • Rebecca Hunt-Foster
  • Christine Janis
  • Diane Kermack
  • Zofia Kielan-Jaworowska
  • Eva Koppelhus
  • Susannah Maidment
  • Erin Maxwell
  • Maria McNamara
  • Henneke Meijer
  • Angela Milner
  • Elizabeth Nicholls
  • Halszka Osmolska 
  • Stephanie Pierce
  • Laura Porro
  • Edina Prondvai
  • Taissa Rodrigues
  • Laura Säilä
  • Bettina Schirrmeister
  • Daniela Schwarz-Wings
  • Mary Schweitzer
  • Jessica Theodor
  • Pat Vickers-Rich
  • Lindsay Zanno 
  • Darla Zelenitsky
And of course to my 2 awesome VP group-mates in Southampton, Aubrey Roberts and Jessica Lawrence Wujek! Also if people are interested in more, check out Trowel Blazers which is devoted to women in palaeontology, archaeology and geology!